Laboratory of Virology, National Institute of Immunology, New Delhi, India
Laboratory of Virology, National Institute of Immunology, New Delhi, India.
J Virol. 2014 Aug;88(16):9141-52. doi: 10.1128/JVI.00619-14. Epub 2014 Jun 4.
HIV-1 modulates key host cellular pathways for successful replication and pathogenesis through viral proteins. By evaluating the hijacking of the host ubiquitination pathway by HIV-1 at the whole-cell level, we now show major perturbations in the ubiquitinated pool of the host proteins post-HIV-1 infection. Our overexpression- and infection-based studies of T cells with wild-type and mutant HIV-1 proviral constructs showed that Vpr is necessary and sufficient for reducing whole-cell ubiquitination. Mutagenic analysis revealed that the three leucine-rich helical regions of Vpr are critical for this novel function of Vpr, which was independent of its other known cellular functions. We also validated that this effect of Vpr was conserved among different subtypes (subtypes B and C) and circulating recombinants from Northern India. Finally, we establish that this phenomenon is involved in HIV-1-mediated diversion of host ubiquitination machinery specifically toward the degradation of various restriction factors during viral pathogenesis.
HIV-1 is known to rely heavily on modulation of the host ubiquitin pathway, particularly for counteraction of antiretroviral restriction factors, i.e., APOBEC3G, UNG2, and BST-2, etc.; viral assembly; and release. Reports to date have focused on the molecular hijacking of the ubiquitin machinery by HIV-1 at the level of E3 ligases. Interaction of a viral protein with an E3 ligase alters its specificity to bring about selective protein ubiquitination. However, in the case of infection, multiple viral proteins can interact with this multienzyme pathway at various levels, making it much more complicated. Here, we have addressed the manipulation of ubiquitination at the whole-cell level post-HIV-1 infection. Our results show that HIV-1 Vpr is necessary and sufficient to bring about the redirection of the host ubiquitin pathway toward HIV-1-specific outcomes. We also show that the three leucine-rich helical regions of Vpr are critical for this effect and that this ability of Vpr is conserved across circulating recombinants. Our work, the first of its kind, provides novel insight into the regulation of the ubiquitin system at the whole-cell level by HIV-1.
HIV-1 严重依赖于宿主泛素途径的调节，特别是针对逆转录病毒限制因子（如 APOBEC3G、UNG2 和 BST-2 等）、病毒组装和释放的拮抗。迄今为止的报道主要集中在 HIV-1 通过 E3 连接酶在分子水平上对泛素机制的劫持。病毒蛋白与 E3 连接酶的相互作用改变了其特异性，从而导致选择性蛋白泛素化。然而，在感染的情况下，多种病毒蛋白可以在不同水平上与这个多酶途径相互作用，使其变得更加复杂。在这里，我们研究了 HIV-1 感染后细胞泛素化的整体调控。我们的结果表明，HIV-1 Vpr 是导致宿主泛素途径向 HIV-1 特异性结果发生重定向所必需且充分的。我们还表明，Vpr 的三个富含亮氨酸的螺旋区对于这一效应至关重要，并且 Vpr 的这种能力在循环重组体中是保守的。我们的工作是此类研究中的首例，为 HIV-1 在细胞整体水平上对泛素系统的调控提供了新的见解。
